Last month, U.S. Immigration and Customs Enforcement released data showing it had achieved a nearly 40 percent spike in immigration arrests in the first 100 days of the Trump administration. In a press call about the new numbers, ICE’s Acting Director Thomas Homan explained that these elevated numbers stemmed from the White House’s decision to reverse aNovember 2014 Obama policy prioritizing certain criminal aliens and recent border crossers for arrest. “These statistics reflect President Trump’s commitment to enforce our immigration laws fairly and across the board,” Homan said.

The arrest total in Trump’s first 100 days—41,898—represents an increase of more than 10,000 over the same period last year. It’s important to note, however, that these numbers don’t reach the former administration’s immigration arrest levels from prior to November 2014, when ICE Enforcement and Removal Operations agents worked with much the same latitude they have today. During the same 100-day period in 2014, for example, ICE Enforcement and Removal Operations made 54,484 arrests, with that number representing a slight decline from the even higher rates of arrest in 2012 and 2013.

If the federal rules and priorities are the same now as they were in the early 2010s, then why have arrests dipped? Narrowing in on the data at a regional ICEfield office level provides a possible answer: The growing sanctuary city movement may be affecting ICE’s ability to get back to its previous arrest capacity.

verseen by ICE’s Los Angeles and New York field offices, have not come close to their 2014 arrest levels. By contrast, arrests have exceeded 2014 levels in regions like Dallas and St. Paul, which have large swaths of territory without sanctuary protections. (Note: ICE field office regions extend far beyond the cities they are named after. For example, the St. Paul field office includes Nebraska, South Dakota, and North Dakota.) The maps below show total arrests per field office between Jan. 20 and April 29, 2014 as compared to the same dates in 2017. The larger the bubbles, the more arrests per field office; click on the bubbles to see precise numbers.

ery broadly, sanctuary city policies—which have been adopted in places likeSan Francisco (in May 2014), Los Angeles (July 2014), and New York City(November 2014)—shield unauthorized immigrants from federal immigration enforcement by ensuring that local authorities do not, for instance, question residents about their immigration status or use local jail systems to funnel arrestees into deportation proceedings. Since 2014, city leaders and sheriff’s and police departments in the above cities and others began honoring far fewer ICEdetainer requests—that is, requests to hold unauthorized immigrants past their release dates to give ICE the opportunity to pick them up from local jails. Between Jan. 20 and April 29, 2014, ICE agents in the Los Angeles field office made 6,209 arrests; during the same period this year, they made 2,273. In that same 2014 time period, ICE agents in San Francisco and New York made 2,870 and 1,458 arrests respectively. They made just 1,976 and 687 arrests respectively between Jan. 20 and April 29, 2017.

Ira Mehlman, spokesman for the Federation for American Immigration Reform, which advocates for stricter immigration enforcement, argues that we should not expect ICE to immediately reach 2014 arrest rates. “It takes time to get back in the groove here,” says Mehlman, citing the Trump administration’s need to replace Obama-era appointees with new personnel in leadership positions. Jessica Vaughan of the Center for Immigration Studies, a think tank that favors restricting immigration, adds that ICE’s dramatic increase in arrests compared to the final two years of the Obama administration is “a very good start.” Vaughan, however, notes the difficulties that sanctuary cities have caused ICE enforcement agents. “In places like California, New York, and Philadelphia ICE was no longer able to arrest criminal aliens while they were in local custody, so they had to go out and find them in the community,” she explains via email. “Some sanctuary jurisdictions have recently reversed their policies, but it will take some time for the administration to implement new policies to address that problem.”

In discussing the new arrest spike last month, Homan acknowledged the logistical difficulties that sanctuary cities pose to ICE agents. “To arrest people at-large rather than in the county jail, it takes longer, it takes more resources, it’s less efficient,” said Homan. He later added, “If people get released, now there’s several people out in the general public, we may not know where they are. So it is gonna take a team of officers to locate that person and do a lot of investigative research on where we can find them.”

This pattern of arrest spikes in non-sanctuary cities is not entirely consistent. Some field offices in non-sanctuary-dense regions such as San Antonio and El Paso, Texas, have not reached 2014 arrest levels. There are also a few regions with major sanctuary jurisdictions that have actually seen an increase in arrests. It is difficult to make definitive assertions about the degree of this trend nationwide, given that ICE field offices cover large swaths of territory and the fact that sanctuary city policies differ nationwide. However, of the nine field office zones that have higher arrest rates in 2017 than 2014, just three—Boston, Philadelphia, and St. Paul—appear to have more than a handful of sanctuary jurisdictions, as per the Center for Immigration Studies’ most recent sanctuary cities map. By contrast, of the nine field office zones with the lowest 2017 arrest numbers compared to 2014, four contain six or more sanctuary jurisdictions and two—New York City and San Diego—have small field office zones that are well-covered by city and county sanctuary policies, respectively.

John Sandweg, the acting director of ICE from 2013 to 2014, cautions that regional variations in ICE arrest numbers could be due to varying institutional capacities across ICE field offices rather than sanctuary policies. “The sample size remains relatively small and could be a byproduct of a wide array of operational issues,” says Sandweg via email. While Vaughan echoes these caveats, she points out that the dramatic drop in ICE arrests in California suggests that those jurisdictions’ widespread refusal to cooperate with ICE, especially on detainer requests, is having a significant effect. “It’s hard to know for sure without more granular statistics, but I think it is notable that the arrests by the California field offices of ICE in particular have gone down so much and been slower to recover, because that state is the biggest and most populous sanctuary jurisdiction in the country,” Vaughan says.

Though ICE’s arrests of unauthorized immigrants, with or without criminal histories, have still not matched the records set by the Obama administration, immigrants’ rights advocates contend the Trump regime has returned to immigration enforcement policies that round up people who do not pose any danger to society. The maps below show arrests of unauthorized immigrants without criminal records per field office between Jan. 20 and April 29, 2014 as compared to the same dates in 2017.

As can be seen in the maps, several ICE field offices, particularly in the South, have hiked their noncriminal alien arrest numbers—in a few cases surpassing 2014 levels. Witold J. Walczak, legal director for the ACLU of Pennsylvania, says the large jump in noncriminal arrests, including in the region served by the ICE Philadelphia field office, can be attributed to the agency’s new willingness to arrest unauthorized immigrants who are found in the vicinity of planned enforcement actions. “They are extremely aggressive now in trying to get into houses, and they question anybody in the area resulting in collateral pick-ups,” says Walczak, whose advocacy work is based in southwestern and central Pennsylvania. “But we’ve also seen a good number of raids, either going to worksites, like factories and construction sites, or pulling over work vans. My perception is these are often not targeted operations, just straight up ethnic profiling.”

Adrian Smith, a spokesperson for ICE’s Philadelphia field office, disputes these claims, saying in an email that ICE’s enforcement actions are “targeted and lead driven.” Asked about his office’s large increase in noncriminal unauthorized immigrant arrests, Smith notes that ICE no longer exempts classes or categories of removable aliens from potential enforcement. “All of those in violation of immigration laws may be subject to immigration arrest, detention, and if found removable by final order, removal from the United States,” says Smith.

Former ICE officials argue that this increase in noncriminal arrests stems from President Trump’s reversal of the previous administration’s immigration enforcement priorities. “ICE has a finite number of resources. During the Obama administration, all of those resources were dedicated to the identification and removal of criminal aliens,” says Sandweg. “As the new administration directs officers and agents to broaden their focus and places equal priority on noncriminals, resources that were previously dedicated to criminal aliens are expended against people who pose no threat.”

ICE’s apparent attempts to dial up arrests on unauthorized immigrants regardless of their criminal histories means America’s cities will necessarily be in its crosshairs. According to Pew, 61 percent of the nation’s estimated 11.1 million unauthorized immigrations live injust 20 major metropolitan areas. The Trump administration has already succeeded in pushing several jurisdictions to reverse sanctuary protections. In February, citing federal funding threats, Florida’s Miami–Dade County, which includes the city of Miami, reversed a policy limiting cooperation with ICE detainer requests. The same month, the city of Dayton, Ohio, reversed a policy prohibiting police from contacting ICE in cases involving misdemeanor violations and felony-level property crimes.

Whether federal pressure will continue to bring other cities into line with immigration authorities remains to be seen. But without local compliance, ICE will have a significantly tougher time ratcheting its arrest levels up to the levels reached by the Obama administration in the early 2010s.